| Date: | 23–29 August |
| Category: | ATP Challenger Tour |
| Draw: | 32S / 16D |
| Location: | Prague, Czech Republic |
| Surface: | Clay |
| Champs: |  Franco Agamenone |
| Champd: |  Victor Vlad Cornea / Petros Tsitsipas |
| Before Name: | RPM Open |
The 2021 IBG Prague Open was a professional tennis tournament played on clay courts. It was part of the 2021 ATP Challenger Tour. It took place in Prague, Czech Republic between 23 and 29 August 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Russian Federation | Evgeny Karlovskiy | 290 | 1 | |
| Alexander Ritschard | 300 | 2 | ||
| Russian Federation | Evgenii Tiurnev | 310 | 3 | |
 France | Geoffrey Blancaneaux | 311 | 4 | |
 Czech Republic | Jonáš Forejtek | 315 | 5 | |
 Belgium | Michael Geerts | 319 | 6 | |
| Romania | Filip Jianu | 320 | 7 | |
 Serbia | Miljan Zekić | 324 | 8 |
The following players received wildcards into the singles main draw:
Martin Krumich Andrew Paulson Daniel SiniakovThe following player received entry into the singles main draw using a protected ranking:
The following players received entry from the qualifying draw:
See main article: 2021 IBG Prague Open – Singles.
Franco Agamenone def. 
Ryan Peniston 6–3, 6–1.See main article: 2021 IBG Prague Open – Doubles.
Victor Vlad Cornea / Petros Tsitsipas def. Martin Krumich / Andrew Paulson 6–3, 3–6, [10–8].
